The invention relates to a car lift for motor vehicles.
In order to lift motor vehicles, particularly for maintenance or repair or for lift systems in parking garages, car lifts are known comprising at least a first and a second lift element, each comprising a hydraulic cylinder/piston assembly for lifting the motor vehicle. In order to lift the motor vehicle, each cylinder/piston assembly is supplied with an inlet for hydraulic fluid, such as hydraulic oil, and the hydraulic fluid displaced by the piston is drained via an overflow. Here, it is known to form the assemblies as a master/slave system. Here, the first cylinder/piston assembly is embodied as a master assembly, by connecting its overflow in a fluid-conducting fashion to the inlet of the second cylinder/piston assembly embodied as a slave assembly.
Such car lifts are known in numerous embodiments. For example, it is known to embody the car lifts as plungers, which are typically arranged underneath the vehicle to be lifted. Additionally, it is known to embody the lift elements as lifting columns, with at least one lifting column being arranged on one side of the vehicle and the second lifting column at the opposite side of the vehicle. Additionally, the embodiment of a car lift is known in the form of a scissor platform, in which the lifting elements are each embodied as lifting scissors. Depending on the weight of the vehicle and the size of the vehicle such car lifts comprise two or more lifting elements.
All above-mentioned embodiments are suitable for the present invention.
The use of at least two cylinder/piston assemblies in a master/slave system is subject to malfunction such that due to thermal expansion and/or air enclosures in the hydraulic system the synchronization between the master and the slave assembly may be disturbed, so that a tilted position of the car lift can develop in parts of the hydraulic system, particularly in the lifted position and/or at pressure peaks.